Transcribed from several documents received from Roger Griffiths - His source: Public Records Office, Kew.
The info has been supplemented with information received from Rainer Kolbicz (station numbers and ships in Halifax section).
Please compare with A. Hague's listing for this convoy at ships in all SC convoys. See also SC escorts.

I have added the details on ships sunk and casualties with the help of:
"The Allied Convoy System", Arnold Hague
"Axis Submarine Successes of World War Two", Jürgen Rohwer"The World's Merchant Fleets 1939". R. W. Jordan
"Lloyd's War Losses", Vol I and Vol II.

The Rescue Vessel Melrose Abbey was on her 6th voyage as such, having started this voyage from Clyde with the westbound Convoy ON 163 on Jan. 24-1943 - to Halifax Febr. 13, then returned to Clyde with SC 121.

Here are some charts showing the progress of, and U-boat sightings/attacks on Convoys SC 121, HX 228, SC 122 and HX 229. The chart has been split into 3 sections. Click on the pictures to get a larger version. Please let me know if they need to be made larger. As will be seen, I've overlapped the sections slightly (see also the analysis of the attacks):

The following ships were torpedoed - SC 121Dates are according to German time and the U-boats named below are those given by J. Rohwer in his "Axis Submarine Successes of World War Two". However, these may now need to be amended as new information is coming to light. For instance, Rainer Kolbicz (Uboat.net) has told me that Empire Impala could not have been sunk by U-591 on March 7 because one of the escorts came across this undamaged straggler several hours after the reported attack. This means that every single U-boat attack reported as successful now has to be checked and compared to the Allied losses.

Egyptian, voyage from Lagos and New York for London with 4926 tons of oil seeds, 31 tons rubber, 710 tons palm oil, 1013 tons tin ore and 9 tons sundries, is said to have been sunk on March 7 by U-230. She had a crew of 38 and 9 gunners, 35 crew and all the gunners perished.
Arnold Hague agrees with 44 dead, but Uboat net (external link) gives her a complement of 49, saying 46 died, 3 survived and were picked up by the escorting HMCS Rosthern.

Empire Impala, on a voyage from New York to Hull with 7628 tons of general cargo, is said to have been sunk March 7 by U-591, after having lagged behind to pick up survivors from Egyptian. There were no survivors.
Arnold Hague gives 48 dead, while Uboat.net says 41 lost their lives.
This ship is not included in "Lloyd's War Losses" Vol. I; she is, however, mentioned in Vol II under "missing and untraced", saying she was posted missing on Apr. 28-1943, having been due at Loch Ewe on March 13-1943, crew of 42 and 6 gunners.

Empire Lakeland, voyage New York-Glasgow with 7805 tons of refrigerated and general cargo, became a straggler and is said to have been sunk March 8 by U-190. There were no survivors.
This ship is not included in "Lloyd's War Losses" Vol. I; she is, however, mentioned in Vol II under "missing and untraced", saying she was posted missing on Apr. 28-1943, having been due at Glasgow on March 13-1943, crew of 57 and 8 gunners, for a total of 65 (Uboat.net gives 64).

Fort Lamy, on a voyage from Philadelphia and New York for Liverpool with 6333 tons of general cargo and explosives as well as a landing craft on deck, became a straggler and is said to have been sunk March 8 by U-527. The landing craft, LCT 2480 was also lost with Fort Lamy. She had a crew of 42 and 7 gunners, 40 crew and 6 gunners died.
These numbers (from "Lloyd's War Losses", Vol I) disagree slightly with what Uboat.net has. The site states she had a complement of 51 and agrees that 46 died, but adds that 3 crew and 2 gunners were picked up almost 2 weeks later by HMS Vervain.

Vojvoda Putnik, cargo of wheat for London, became a straggler and is said to have been sunk March 8 by U-591. 44 died.
This ship is not included in "Lloyd's War Losses", Vol I; she is, however, mentioned in Vol II under "missing and untraced", saying she was posted missing on Apr. 28-1943, having left Bahia Blanca on Dec. 13-1942 for Loch Ewe and London, left New York on Febr. 23-1943, in W/T on March 8 in 58 42N 31 25W - "S.O.S. - abandoning ship", 7900 tons wheat, crew of 38 and 6 gunners.

Guido, which according to J. Rohwer became a romper, was on a voyage from St. Kitts and New York for Greencok with mail, 4242 tons of sugar and 35 tons of cotton, and is said to have been sunk on March 8 by U-633. She had a crew of 37 and 8 gunners, 8 crew and 2 gunners died.
(Uboat.net adds that the 35 survivors were picked up by USS Spencer).
R. W. Jordan gives U-526 as the culprit for this attack.

Leadgate, on a voyage from New York to Liverpool, became a straggler and is said to have been sunk on March 8 by U-642, with the loss of all on board.
This ship is not included in "Lloyd's War Losses", Vol I; she is, however, mentioned in Vol II under "missing and untraced", saying she had left St. John, NB on Febr. 21-1943, left Halifax on Febr. 25, posted missing on Apr. 28-1943, having been due at Mersey on March 14, 2700 tons of flour, crew of 26 and 4 gunners (Uboat.net gives 26 all total).

Malantic, voyage New York for Barry with general cargo, including 6000 tons bombs and 5000 tons ammunition, is said to have been sunk on March 9 by U-409. 25 died out of a complement of 46 (Uboat.net says complement of 47). Melrose Abbey located a lifeboat with 11 survivors, 10 of whom, including the captain, was brought on board. The 11th, however, was swept away and drowned, despite a Rescue Ship officer diving in to assist him. A further search located a 2nd lifeboat, and 10 more survivors were recovered with great difficulty. This boat capsized during the recovery, and several other occupants were trapped and died.

Rosewood, voyage from New York to Clyde with a cargo of fuel oil, is said to have been sunk March 9 by U-409. She had a crew of 33 and 9 gunners, all perished. "Lloyd's War Losses" adds: "Reported in 58 30N 20 31W on March 11, presumed sunk". R. W. Jordan (and Uboat.net) adds that she was scuttled by gunfire by the U.S. Coast Guard cutter Bibb in that position on that day.

Milos, cargo of steel and lumber for Grimsby, became a straggler and was believed to have been sunk on March 9 by U-530, there were no survivors. See also this story in my "Warsailor Stories" section, re. someone who served on this ship at the time.
Arnold Hague gives sinking date as March 11, 30 died, while R. W. Jordan gives 28 casualties, same date (here's Uboat.net's account).
This ship is not included in "Lloyd's War Losses" Vol I; she is, however, mentioned in Vol II under "missing and untraced", saying she was posted missing on Apr. 28-1943, having been due at Loch Ewe on March 13, crew of 30.

Nailsea Court, voyage from Beira, Table Bay and New York for London with mail and 7661 tons of general cargo, including copper bars, nickel ore and asbestos, is said to have been sunk on March 10 by U-229. She had a crew of 37, 9 gunners and 2 passengers - 34 crew, all the gunners and the 2 passengers were lost. 1 survivor was picked up by Melrose Abbey, which had found a raft with 2 men on it, but 1 of them was trapped in the raft and drowned (they had been on the raft for about 8 hours).
R. W. Jordan says 45 died, 5 survived. Uboat.net says there were 49 on board, 4 survived, 3 of whom were picked up by HMCS Dauphin.

Coulmore is said to have been damaged in the same attack by U-229. According to Uboat.net 25 died in this attack, out of a complement of 43.

Bonneville, on a voyage from New York to Liverpool with general cargo and explosives, as well as a landing craft on deck, is said to have been sunk on March 9 by U-405. However, Rainer has told me that new findings now indicate that U-229 may have been responsible for this loss. This then, leaves the question of who was attacked by U-405(?). See also by page about Bonneville, which includes transcripts of all the statements given at the subsequent inquiry, as well as a crew list. Only 7 survived, 4 of whom were rescued from a capsized lifeboat by Melrose Abbey, 1 was picked up from another boat by the same vessel, while 2 were saved by USCGC Bibb, which had arrived on March 9 to reinforce the escort (together with the cutter Ingham and destroyer Babbitt). When Bonneville was sunk, the landing craft LCT 2341 was also lost.